Process of joining by means of polyhalogen compounds

ABSTRACT

Molecules of low molecular weight polymers derived at least in part from a diene monomer, are joined to produce branched polymers and copolymers of increased molecular weight. The polymers which are joined are live polymers, i.e., they have one or more &#39;&#39;&#39;&#39;live ends.&#39;&#39;&#39;&#39; The joining agents consist of, or comprise, a saturated or unsaturated, straight or branched chain or cyclo-containing aliphatic hydrocarbon which contains one to 50 or more carbon atoms and comprises three or four halogens on a terminal carbon. 1This application is a continuation-in-part of my application Ser. No. 575,967 filed Aug. 30, 1966 (now abandoned).

United States Patent 1 1 Halasa 1 June 5, 1973 [541 PROCESSOF JOINING BYMEANS OF 3,091,653 5/1963 Nogradi .,....26o 681.5 POLYHAL EN C MP ND3,135,716 6/1964 Uranech etal...... .....260/45.5 3,281,383 10/1966Zelinski et al ..260/23.7 1 Invenm" Adel flalasalBathi 01110 3,318,8625/1967 Hinton ..260/94.2 [73] Assignee: The Firestone Tire & Rubber3,382,225 5/l968 Naylor ..260/94.3

P y. Akron, Ohio FOREIGN PATENTS OR APPLICATIONS 1 Filed= 2, 1971992,210 5/1965 Great Britain ..260/94.7

' 21 A l.N 112 026 1 PP 0 Primary Examiner-Joseph L. SChOfeI' RelatedU.S. Application Data Assistant Examiner-William F. HammockAttorney-+Gordon C. Mack [63] Continuation of Ser. No. 864,825, Oct. 8,1969, abandoned, and a continuation-in-part of Ser. No. $75,967, Aug.30, 1966, abandoned. [57] ABSTRACT Molecules of low molecular weightpolymers derived 52 U.S. c1. ..260/94.2 M, 260/80.78, 260/821, at leastin p from diene monomer, are joined to 260/83.7,260/85.3,260/85.l,260/94.7R Produce branched P y and copolymers of 51 1m.c1..C08d 5/04, C08d 3/08,C08d 3/12 creased molecular weight The P y whichare 58] Field of Search ..260/94.2 M, 94.7 HA, joined are live Polymers,y have one or more 260/94 7 R live ends. The joining agents consist of,or comprise, a saturated or unsaturated, straight or branched [56]References Cited chain or cycle-containing aliphatic hydrocarbon whichcontains one to 50 or more carbon atoms and com- UNITED STATES PATENTSprises three or four halogens on a terminal carbon.

3,078,254 2/1963 Zelinski et a]. ..260/45.5 6 Claims, 2 Drawing FiguresPATENTEDJUN' 5 I913 3. 737, 421

FIG. 30

0.00 Cl/Li AMOUNT POLYMER O I l GPC- COUNTS FIG. 2 30 CI/Ll l.5-2.0AMOUNT 20 POLYMER m 32 30 28 26 24 G P C CO UNTS PROCESS OF JOINING BYMEANS OF POLYHALOGEN COMPOUNDS This application is acontinuation-in-part of my application Ser. No. 575,967 filed Aug. 30,1966 (now abandoned).

The invention relates to novel branched polymers and to a novel methodof making them. The term polymer is used herein to include bothhomopolymers and copolymers.

Polymers of diene monomers often are difficult to fabricate into usefulshapes and commercially practical products or are deficient in physicalproperties desired for such shapes or products. Such polymers includehomopolymers of conjugated dienes of four to six carbon atoms (e.g.butadiene, piperylene, isoprene, 2,3- dimethylbutadiene) and copolymersthereof (e.g. butadiene-isoprene, piperylene-butadiene, etc.) andcopolymers of such conjugated dienes with isobutylene (butyl rubber),styrene, a hydrocarbon-substituted styrene such as methylstyrene andethylstyrene, copolymers of butadiene and isoprene with styrene or suchsubstituted styrenes, natural rubbers, chloroprene and copolymersthereof with butadiene and/or isoprene and/or styrene or an EPDM rubber(i.e., a rubber in which ethylene and propylene are copolymerized withan unconjugated diene of about five to 12 carbon atoms which may bedicyclopentadiene, cyclooctadiene, hexadiene-l,4, methylene norbornene,ethylidene norbornene or other non-conjugated diolefin. Block copolymersas well as other copolymers can be used. The foregoing include theso-called stereo rubbers which have been of great interest in recentyears, but the properties of most of these new synthetic rubbers havenot been completely satisfactory for all uses, as witness the widespreadpractice of blending such rubbers with natural rubber or emulsion SBR.

The stereo rubbers may be produced by polymerization of isoprene orbutadiene-l ,3 by means of a catalyst which is a hydrocarbon-solublehydrocarbon derivative of an alkali metal, for example, an alkyl,alkenyl, cycloalkyl, cycloalkenyl, aryl or alkaryl derivative. Preferredlinear polymers of diene monomers are prepared by polymerization of aconjugated diolefin by means of a lithium-hydrocarbon catalyst in theabsence of air and moisture; copolymers of butadiene and isoprene or ofeither or both such diolefins with styrene or methylstyrene are producedby the same technique.

The preferred polymerization catalyst is nbutyilithium. Derivatives ofthe alkali metals (and particularly lithium, sodium and potassium) whichare catalysts include the ethyl, butyl, amyl, hexyl, cyclohexyl,

2-ethylhexyl, n-dodecyl, n-hexadecyl, allyl, benzyl,

crotonyl, cyclohexenyl, camphyl, isobornyl, phenyl,

tolyl, xylyl, naphthyl and xenyl alkali metals as well as di-metalderivatives which include derivatives of ethyl- Y ene, trimethylene,tetramethylene, decamethylene and octadecamethylene; 1,2-dimetalatedpropane, 1,4- dimetalated benzene, l,5 dimetalated naphthalene, l,-Z-dimetalated-l,B-(diphenyl) propane, etc. The polymerizations areusually carried out at atmospheric pressure, but pressures greater andless than atmospheric may be employed. The reaction is advantageouslycarried out in a hydrocarbon compound, preferably a nonether and usuallypentane or hexane, usually at an elevated temperature below thetemperature of the boiling point of the solvent, but higher temperaturesmay be used and temperatures as low as 70 C. or lower may is required,and usually from about 0.001 to about 0.5 gram of catalyst will beemployed for each 100 parts of the monomer. Such linear polymers arecharacterized by high 1,4-content (-95 percent of polymer derived frombutadiene or isoprene), when produced in a hydrocarbon solvent. They arecharacterized by high linearity and narrow molecular weightdistribution. The vulcanizates of such polymers are characterized byexcellent physical properties, including high resiliency, lowhysteresis, excellent resistance to abrasion, low running temperaturesand excellent flexibility and retention of other good physicalproperties at extremely low temperatures typical of the Arctic inwinter, all in comparison with standard emulsion polymerizates, such ascommercial SBR. However, such lithiumcatalyzed polymers are moredifficult to process in standard rubber equipment, such as banburymixers, mills and tubers, as compared to natural rubber and conventional(emulsion) SBR, so that they are usually mixed with natural rubberand/or SBR for commercial use. Certain of such polymers produced bylithium catalysts also possess undesirable cold-flow properties.

There are other diene polymers produced by polymerization of butadieneand/or isoprene with or without other monomers, e.g., styrene, etc., bymeans of other catalysts. Polymers of lower 1,4-content are produced bylithium catalysts in the presence of Lewis bases. All such dienepolymers may be treated by the process of this invention.

It is an object of the invention to overcome the disadvantages of anysuch polymers of diene monomers, to provide novel branched polymers ofhigh molecular weight having unexpectedly improved properties and toprovide a novel method of making the novel poly-- mers.

The polymers used in the invention are rubbers. Often they are liquidrubbers (having molecular weights of 1,000 to 30,000) or soft rubbers(having average molecular weights up to about 300,000 but useful resultsare obtained with polymers of higher molecular weights (as high as about2,000,000). Rubbery products are obtained by joining polymers of suchlower molecular weights.

In accordance with the invention, the polymer treated is a live polymer,i.e., it has one or more live ends. A relatively low molecular weightlive polymer of a diene monomer or copolymer derived at least in partfrom a diene monomer, is reacted with a joining agent which comprises asaturated or unsaturated, straightor branched-chain or cyclo-containingaliphatic hydrocarbon which includes one to 20 or 50 or more carbonatoms per molecule and three or four halogens attached to a terminalcarbon atom. The joining agent may comprise other electron-withdrawinggroups. Such electron-withdrawing groups may or may not enter into thejoining reaction. Such electronwithdrawing groups include ketone,aldehyde, ether, hydroxy, oxide, nitro-vinyl, ester, anhydride, amine,acid, thio, sulfonate, sulfide and unsaturated, etc. groups. Thehalogens of the joining agent may be fluorine, chlorine, bromine and/oriodine or mixed halogens.

The process of the invention includes reactions of one or more suchpolymers, with one or more of the halogen-containing joining reagents ofthis invention. The process of the invention is carried out at anytemperature at which appreciable reaction occurs, generally in the rangeof 75 C. to 275 C. and prefer-ably in the range of C. to 150 C. Thereaction can be carried out under reduced pressure, atmospheric pressureor at super-atmospheric pressures. Especially when the reaction isconducted in a volatile solvent or solvent mixture containing a volatilefraction, superatrnospheric pressures are convenient to allow use ofreaction temperatures above those to which the reaction would beconfined at atmospheric pressure.

In the reaction of the invention there is normally utilized sufficientlive polymer to provide from 0.01 to and preferably.0.l to 1.0equivalent of alkali metal per atom of halogen contained in thehalogen-containing compound. The mechanisms by which the reaction of theinvention increases molecular weights of polymers is not known but mayinvolve formation of radicals of which the halogen-containing compoundsare precursors.

The joining agent may comprise a single carbon atom, such as chloroformor carbon tetrachloride, or a corresponding bromide or fluoride, or itmay be a higher molecular weight com-pound such as 1,1 ,1-trichloropentane, l ,1 ,l-tribromopentane, 1,1,1- trichloropropane,l,l,l-trichloro-n-butane, l,l,ltrichloro-2-methylpropane, l ,1 l-trichloro-n-hexane, cyclohexylme'thyl trichloride, l ,2-dichloro-4,4,4-tribromo butane, l l l -triiodo-2-methylpropane, l l l-tribromo-n-hexane, bis( 3 ,3 ,3-trifluoropropyl) ether, 1 ,l l-trichloro-3 ,7-decadiene, bis(5 ,5 ,5- triiodomayl) ether,bis(2,2,2-trichloroethyl) ether, etc.

The joining agent is added to the live polymer or copolymer, usually insolution. It is added to the reaction mixture after substantialcompletion of the polymerization reaction.

The novel polymers produced by the invention from polymers produced withhydrocarbon-lithium catalysts are characterized by improved processingproperties, in comparison with polymers which have not been reacted inaccordance with the invention or in comparison with similar polymersproduced by other catalysts, such as Ziegler catalysts, etc., and havingmolecular weights comparable to those of the novel polymers. The novelpolymers arerubbery and behave in rubber mills, banbury mixers andextruders as satisfactorily as do emulsion polymers of the conventionalSBR types. The novel rubbery polymers are readily utilized in practicalrubber compounds without admixture of natural rubber or conventionalSBR, although such other rubbers can be mixed with the novel polymers ifdesired.

The novel polymers have higher average molecular weights, normallyaveraging 20 per cent to several hundred per cent higher than theaverage molecular weight of the polymer before reaction in accordancewith the invention. The novel polymers are highly branched.v

They are solids with reduced (or no) tendency to coldflow and present nopackaging or shipping problems. The novel rubbery polymers can beextensively diluted with oil (as with 37.5 parts oil per 100 partspolymer) from the stereo synthetic rubbers also, surprisingly, possessthe high resilience, high efiiciency, low running temperature, highdynamic modulus and low internal I friction properties characterizingthe starting polymers, and hence are much superior in these respects tovulcanizates of conventional emulsion polymers.

The process of the invention increases the molecular weights of polymersand reduces linearity, producing branching and cross-linking; it can beutilized, if desired to cross-link a polymer to a stage where the novelpolymer displays vulcanizate properties. Such novel Vulcanizates haveadvantages because the cross-links in their structures do .not involvesulfur or oxygen linkages but carbon-to-carbon cross-links.

FIGS. 1 and 2 are gel-permeation chromatograph (G.P.C.) curves showingthe efi'ect of joining with carbon tetrachloride as will be explained inconnection with Example 1.

The invention is illustrated by the following examples, in which partsare expressed by weight unless 0therwise indicated.

EXAMPLE 1 (0.56 on the curve) the molecular weight distribution wasbroadened and the peak shifted to the right. This is a relativelystraight-chain polymer. When more carbon tetrachloride was added in theamount of 1.00 to 1.50 chlorine per lithium (the ratio of chlorine tolithium), the peak of the curve shifted further to the right, appearingat 27 G.P.C. counts, and the curve shows still broader molecular weightdistribution.

FIG. 2 is a similar series of curves comparing the effects of polymerwhich was not being joined,with the effect of using CCl at a chlorine tolithium ration of one, adding all of the CC1. at one time, and also theeffect of using 1.5 and 2.0 chlorine to lithium ratios, adding all ofthe CCl at one time. The joined polymer resulting from the latter,showed a G.P.C. peak height at 28, and a broader molecular weightdistribution than that of the control, indicating that additional carbontetrachloride indeed caused joining of the polybutadiene polymers togive a higher molecular weight joined material. I

TABLE 1 Weight Fraction (W of Joined Polybutadiene DlMER TRIMER Cl/Li M.W. Y

This table shows the weight fraction (W of joined polybutadiene in whichthe joining agent was carbon 90,500. When the chlorine to lithium ratiowas 1.0, the

M, value was 152,000 and the per cents of dimers and trimers found was.808 and .606. This table points out that carbon tetrachloride used asjoining agent indeed increases the molecular weight and broadens it.

EXAMPLE 2 Five glass beverage bottles were used as pressure reactionvessels. Each bottle was charged with 200 ml. of a hexane solutioncontaining 30 grams of butadiene- 1,3. To each bottle was added 4.0 ml.of a nbutyllithium solution in hexane containing 0.005 gram ofcarbon-bound lithium per ml. of solution. Each bottle was tightly sealedand placed for two hours in a polymerization water bath maintained at 50C., the contents of each bottle being agitated by movement of thebottles in the bath in a conventional manner. The bottles were removedfrom the 50 C. bath and varying amounts of a hexane solution containing0.002 gram of carbon tetrachloride per ml. of solution were added to thebottles. Then the bottles were placed in a water bath maintained at 70C. and moved therein in a conventional manner for 16 hours to allow forreaction between the live polymer and carbon tetrachloride. The contentsof each bottle were coagulated by mixing with methanol, the rubberypolymer in each case was separated and dried, and then Williamsplasticity measurements were made on each polymer. Results are shown inTable II, in which the control polymer is designated Polymer 1A, andPolymers 1B through 1E represent polymers from the bottles to whichincreasing amounts of carbon tetrachloride were added.

TABLE I] Williams Plasticity Hgt. in 1.0 min. reml. CCI. mm. afterHeight in mm. covery after Polymer Solution 3 min. After 7.5 min. 7.5min. load 1? T) 2.97 2.50 18 0.4 3.26 2.76 0.36 1C 0.8 3.71 3.25 0.48 1D1.2 4.00 3.43 0.84 115 1.6 5.07 4.33 2.27

In accordance with ASTM Designation: D 926-56, published in ASTMStandards on Rubber Products, pages 472-474 (1957), except that testswere made at room temperature (about 23 C.), no talc was used andrecovery values are actual measurements in mm.

Table I1 disclosed that as the carbon tetrachloride was increased theresulting polymers showed increasing Williams plasticity values andsharply increasing recovery values, indicating that the molecularweights of the with carbon tetrachloride to produce new polymers ofincreased molecular weight which have a broad molecular weightdistribution and improved processability.

EXAMPLE 3 An autoclave of approximately 1.9 liter capacity was chargedwith 1322 grams of a hexane solution containing 25 percent ofbutadiene-1,3. The solution was stirred in the autoclave and then two100 m1. samples (totaling 122 grams) were removed for determination ofimpurities reactive with butyllithium. The impurity level for thereactor containing the 1200 grams of butadiene-hexane solution was foundto correspond to 0.852 millimole of'butyllithium. Thereupon 58.6 ml. ofa n-butyllithium solution in hexane, containing 0.073 millimole ofbutyllithium per ml. of solution, was added to the autoclave, providing3.426 millimoles of butyllithium for polymerizing the 300 grams ofbutadiene in the autoclave, in addition to the 0.852 millimole needed toneutralize impurities. The reaction temperature was maintained atapproximately 40 to 70 C. for three hours, at which time approximately100 percent conversion of the butadiene to polybutadiene had occurred,as indicated by the fact that the reaction solution contained 25 percenttotal solids. A control sample of polymer solution (25 percent of thereaction mixture) was removed from the autoclave and coagulated bymethanol; the polymer is designated Polymer 3A in Table 111. Fourincrements of a hexane solution each containing 0.05 millimole of carbontetrachloride per ml. of solution were then added to the live polymer inthe autoclave at 15-minute intervals, and a sample of the reactionmixture was removed from the autoclave immediately prior to eachaddition of the chlorinecontaining compound. A first such increment, 3.2ml., was added immediately and after removing the 25 percent sample(control sample), and the reaction temperature then'varied from 63 to 42C. Then a second sample was taken and coagulated as before to providePolymer 38, and a second increment of 2.76 ml. of the chloride solutionwas added to the remaining reaction mixture (64.6 percent of original).A third sample was taken and coagulated as before to provide Polymer 3C,and a third increment of 1.90 ml. of the chloride solution, was added tothe remaining reaction mixture (44.5 percent of original). A fourthsample was taken and coagulated as before to provide Polymer 3D, and thefourth increment (1.05 ml. of the chloride solution) was added to theremaining reaction mixture (24.4 percent of original). The reactiontemperature varied between 52 and 57 C. after the second chlorideincrement addition, and this same reaction temperature range wasmaintained overnight for an additional 15 hours. The remaining reactionmixture was taken as the fifth sample, and it was coagulated by methanolas before, to provide Polymer 3E. Table III shows the properties of thefive samples.

TABLE III Williams Plasticity at 23 C.

Dilute Mooney Height in 1 minute recovery Solution viscosity mm. afterafter 3 minutes Polymer Viscosity (ML/4/ 3 minutes under load None ofthe samples contained gel.

"Not determined.

EXAMPLE 4 Butadiene-l,3 was polymerized by the procedure of Example 3.The impurity level for the reactor and contents (l 190 grams) was foundto be equivalent to 1.134 millimoles of butyllithium. A total of 2.9 ml.of a 1.57

molar solution (in hexane) of n-butyllithium was added Each sample ofpolymer solution was coagulated by methanol, and the solid polymer wasdried. Molecular weight distribution (MWD) curves were obtained for thefive polymer samples. The MWD curve for the control, Polymer 4A, showeda sharp peak indicating that nearly all of the material had molecularweights between about 75,000 and 250,000, the peak coming at about115,000. The peak in the MWD curve for Polymer 48 came at about 120,000,but the curve showed a larger amount of relatively high molecular weightpolymer, in the range of about 200,000 to about 800,000. The peak in theMWD curve for Polymer 4C occurred at about 200,000, with appreciablepolymer in the molecular weight range of about 500,000 to about1,000,000. The shape of the MWD curve for Polymer 4D was not'muchdifferent from the shape of the curve for Polymer 4C except that thepeak at the molecular weight of about 220,000 was higher, thus showingthatthe average molecular weight of Polymer 4D was higher than that ofPolymer 4C. The MWD curve for Polymer 4E again contained the peak atabout 220,000, but the curve was broader, showing larger amounts ofpolymer in the molecular weight range of 500,000 to about 1,500,000.

EXAMPLE 5 A substantially constant composition copolymer of butadieneand styrene, containing approximately 18 percent of styrene, wasprepared in a 50-gallon (189 liter) autoclave by the procedure ofBritish Pat. No. 994,726 orCanadian Pat. No. 769,096 or U. S.application Ser. No. 209,706 (all of which comprise substantially thesame disclosure), using n-butyllithium as the polymerization catalystand hexane as the solvent. The Mooney viscosity (ML/4/100 C.) of thecopolymer (Polymer 5A) was 16. Sufficient carbon tetrachloride toprovide one chlorine atomfor each lithium atom added in the butyllithiumpolymerization catalyst was prepared in hexanesolution'and added to thecopoly--- mer solution in the autoclave in five increments, onethird asthe first increment followed by four increments of about one-sixth eachof the chloride solution. The

reaction temperature during addition of the chloride solution incrementsand until completion of the reaction was in the range of 60 to 72 C. Thereaction mixture was stirred for one hour after addition of'said firstincrement and then a portion to provide Polymer 58 was removed from theautoclave, coagulated in methanol and dried; the Mooney viscosity (ML/4]100 C.) of Polymer 5B was 38. The second increment of the chloridesolution was then added to the live polymer in the autoclave, thereaction mixture was, stirred another hour, and a portion was removed toprovide Polymer 5C; the Mooney viscosity (ML/ 4/ 100 C.) of Polymer 5Cwas 43. The third increment of the chloride mixture was then added tothe live polymer, the reaction mixture was stirred for an additionalhour, and a portion was removed to provide Polymer 5D; the Mooneyviscosity (ML/4/l00-C.) of Polymer SD was 54. The

' fourth increment of the chloride solution was added to the livepolymer, the reaction mixture was stirred for 70 minutes, and a portionwas removed to provide Polymer 5E; the Mooney viscosity (ML/4/100 C.) ofPolymer SE was 65. The fifth and final increments of the chloridesolution were then added to the live polymer, the reaction mixture wasstirred for an hour, and a portion was removed to provide Polymer 5F;the Mooney viscosity (ML/4/ 100 C.) of Polymer 5F was 77 The MWD(Molecular Weight Distribution) curve for Polymer 5A (the 'control)showed a peak at 125,000 molecular weight and only a small amount ofmaterial in the molecular weight range of 250,000 to 500,000. However,the MWD curve for Polymer 5F was a much broader curve with a peak at amolecular weight of about 140,000, and a considerable portion of polymeroccurred in the molecular weight. range of about 250,000 to 3,000,000.

, EXAMPLE 6 Example, 5 was substantially repeated to produce asubstantially constant compositioncopolymer of butadiene and styrene,also containing about 18 percent of styrene. After addition of the firstthree of the scheduled four increments of carbon tetrachloride solution(in hexane) to the solution of the live polymer, calculated to furnishone chlorine atom for eachlithium atom in the butyllithiumpolymerization catalyst, a portion of the reaction mixture providedPolymer 6B with a Mooney viscosity (ML/4l100 C.) of 76, consideredsufficiently high for evaluation of the polymer. Polymer 6A, the controlcopolymer which had not reacted'with the chloride solution, provided aMWD (Molecular Weight Distribution) curve similar to the curve forPolymer 5A, except that the peak occurred at a molecular weight of140,000. The MWD curve for Polymer 68 was broad, similar to the curvefor Polymer 5F except that the peak was slightly higher; again, therewas a considerable portion of polymer in the molecular weight range ofabout 250,000 to 3,000,000.

EXAMPLE 7 Polymer SF of Example 5 and Polymer 68 of Example 6 weretested as raw polymers. After coagulation they were diluted with 37.5parts per l parts of polymer with a commercial aromatic diluting oil,and in a tire tread composition containing about 70 parts per 100 ofpolymer of intermediate super abrasion furnace black (I.S.A.F.) andconventional proportions of zinc oxide, stearic acid, antioxidant,processing oil, sulfur and sulfenamide-type accelerator. One suchformula comprises:

Polymer 100 parts Zinc oxide 1.4 parts I.S.A.F. Carbon Black 68 partsStearic acid 2 parts Antioxidant 2.5 parts Aromatic processing oil 40parts Sulfur 1.7 parts Accelerator 1.4 parts The tread compositionscontained the same total amounts of diluting oil, whether added tooil-dilute the polymer prior to compounding, or added only duringWilliams plasticity values for the polymers shown in Table VII-A arecompared in Table VII-B with like values for Control M, a substantiallyconstant composition butadiene-styrene copolymer, containing 18 percentstyrene, made according to the patent disclosure identified in Exampleand comparable to Polymers 5A and 6A except for its higher molecularweight (50 ML/4/ 100 C.); and Control N, likewise comparable to polymers5A and 6A but for a much higher molecular weight (75 ML/4/ 100 C.) andthe fact that it was oildiluted with 37.5 parts per 100 of polymer withthe same commercial aromatic oil used to dilute Polymers 5F and 68.

The oil-diluted Polymers 5F and 68 displayed no objectionable cold-flowproperties, and the tire tread compositions made from them processedvery satisfactorily in a rubber mill and an extruder. In contrast,Control N exhibited objectionable cold-flow properties and provided atire tread composition same formula as used for Polymers 5 F and 68)having unsatisfactory processing characteristics in a rubber mill and anextruder. The vulcanizates of tread compositions made from the polymersshown in Table VII-B all displayed excellent physical propertiescomparable to the properties shown in patent disclosures identified inExample 5 for substantially constant composition copolymers of butadieneand styrene.

EXAMPLE 8 Butadiene-l,3 is initiated with n-butyllithium at 0 C. withoutthe use of hydrocarbon solvent other than the butadiene-l,3, and at 30per cent conversion carbon tetrachloride is added to the live polymercement. The excess monomer is evaporated and the cement is coagulated inthe usual manner with methanol containing a small amount of dissolvedantioxidant, di-t-butyl catechol, added to stabilize the polymer. Thepolymer obtained has a broad molecular weight distribution and is highlybranched and has an increased molecular weight in comparison to themolecular weight of polybutadiene similarly prepared in the absence of ajoining agent.

Chloroform or other joining agent of this invention may be similarlyused.

EXAMPLE 9 A copolymer of butadiene and styrene is prepared usingn-butyllithium initiator at 50 C. During the polymerization, a sample istaken to determine the total solids value, which is related to the percent conversion of the monomers to copolymers, and when per cent of themonomers are converted to polymers a cement of chloroform is added. Acopolymer of broad molecular weight distribution and large degree ofbranching is produced which is useful in the manufacture of tires andrubber goods.

Carbon tetrachloride and other joining agents of this invention may besimilarly used.

The novel polymers can be blended with other 7 known polymers to provideuseful commercial compositions for fabrication into useful shapes andarticles. The novel rubbery polymers are advantageously blended withknown rubbers (e.g., natural rubber, SBR, BR, IR, IlR, CR, ISR), with orwithout diluting oils, for forming vulcanizates of great technicalimportance. The novel rubbery polymers are advantageously compoundedwith the known reinforcing carbon blacks to produce useful commercialstocks, which may also contain one or more additional rubbery polymer,and may also contain 5 to phr (parts per 100 parts of the rubber) ofdiluting oil or plasticizer. Sulfur and other known vulcanizing agentsfor natural rubber and the commercial synthetic rubbers are useful forforming vulcanizable stocks containing a novel polymer of the invention.Known antioxidants, stabilizers and antiozonants for natural andcommercial synthetic rubbers find similar utility in compositionscontaining the novel polymers of the invention. Known methods of mixing,forming, fabricating and curing compositions of natural and commercialsynthetic rubbers are applicable to and useful with compositionscontaining the novel polymers of the invention. The novel polymers ofthe invention are especially useful in pneumatic tire tread, sidewalland carcass compositions, and the considerations of this paragraph areespecially relevant to the use of the novel polymers in tires.

I claim:

1. In the process of preparing a rubbery polymer or copolymer derived atleast in part from a conjugated diene by means of a lithium-basedcatalyst, the improvement which comprises terminating the chain growthreaction with a chain-terminating agent of the class consisting ofcarbon tetrachloride and chloroform and producing a polymer or copolymerof increased molecular weight distribution and, a Williams plasticityrecovery value of at least about 0.84.

2. The process of claim 1 in which the chain terminating agent is carbontetrachloride.

thereof is substantially complete, by reacting same in solution with ajoining agent of the class consisting of carbon tetrachloride andchloroform and producing a polymer or copolymer of increased molecularweight distribution and a Williams plasticity recovery value of at leastabout 0.08.

5. The process of claim 4 in which the joining agent is carbontetrachloride. p

6. The process of claim 4 in which said polymer or copolymer ispolybutadiene and the chain-terminating agent is carbontetrachloride I I

2. The process of claim 1 in which the chain terminating agent is carbontetrachloride.
 3. The process of claim 1 in which said polymer orcopolymer is polybutadiene and the chain-terminating agent is carbontetrachloride.
 4. The process of making a rubbery, highermolecular-weight polymer or copolymer which comprises joining moleculesof a lower molecular-weight lithiated polymer or copolymer derived atleast in part from a conjugated diene monomer after the polymerizationthereof is substantially complete, by reacting same in solution with ajoining agent of the class consisting of carbon tetrachloride andchloroform and producing a polymer or copolymer of increased molecularweight distribution and a Williams plasticity recovery value of at leastabout 0.08.
 5. The process of claim 4 in which the joining agent iscarbon tetrachloride.
 6. The process of claim 4 in which said polymer orcopolymer is polybutadiene and the chain-terminating agent is carbontetrachloride.